Constructing Defect-Rich MoS2/N-Doped Carbon Nanosheets for Catalytic Polysulfide Conversion in Lithium-Sulfur Batteries

摘要

Polysulfide dissolution is one of the inherent challenges in lithium-sulfur batteries (LSBs). The shuttle effect of soluble polysulfide species between the cathode and the anode can cause the loss of active materials and the attenuation of specific capacity in LSBs. Herein, the N-doped porous carbon (NC) nanosheets with uniformly anchored defect-rich MoS2 nanosheets (MoS2/NC) were constructed by a simple and low-cost method. The NC nanosheets facilitate transfer of lithium ion and electron and localize polysulfides via the Li-N chemical bond. The defect-rich MoS2 nanosheets can be used as electrocatalysts to propel polysulfide conversion by abundant catalytic activity sites and thus control the shuttle effect as well as improve cycling performances of LSBs. Consequently, the defect-rich MoS2/NC composites as separator modification present a high specific capacity of 1021 mAh g(-1) at 0.2 degrees C after 100 cycles and superior long-term performances with enhanced specific capacities of 429 mAh g(-1) with a low capacity fading rate of 0.027% per cycle at 5 C after 1000 cycles. The reasonable construct strategy of defect-rich MoS2/NC composites is effective in enhancing the electrochemical performances of LSBs and promoting their commercial applications.